The use of specific materials to inhibit or prevent oxidative degradation of natural or synthetic materials is well known. Many of the materials utilized for this purpose are insoluble in water and toxic to mammals at both high and low levels. Examples of such materials are BHA (butylated hydroxy anisole); BHT (butylated hydroxy toluene); propyl gallate; and alpha-tocopherol. It is known that natural antioxidants are widely distributed in plant tissues. Certain of these antioxidants have been obtained in crude form and have been shown to have an effect on commercial soybean lipoxygenase [J. Food Science, 36: 571 (1971)]. Japanese patent application SHO 58-42686 discloses an alkali-organic solvent extraction process for obtaining an antioxidant from white pepper powder. The Polish publication Medycyna Weterynaryjna 28: 430-433 describes the extraction with boiling distilled water of dried hay or Urtica. The resulting extract was used as an antioxidant for fish meal; it is stated that the extract may be stored until use for not more than 48 hours at 4.degree. C.
The applicants have described in the parent application, antioxidants which are stable under ambient conditions for extended periods, and which may be obtained by water extraction of plant tissues, and that such antioxidants are absorbed percutaneously, and exert an antioxidant effect on the outer and inner layers of the skin. These effects are advantageously obtained when the antioxidant is applied to the skin as a dispersion in a hydrophilic or hydrophobic base. The cosmetic result of the application of the antioxidant comprises a softening of the skin which is detectable by touching with the fingertips. In addition, it was found that the peroxide level of the skin is reduced by application of the antioxidants and that the antioxidants may also be utilized for the preservation of food in place of, for example, BHT or BHA.
The particular plant tissues (e.g. the leaves) mentioned in the parent application, from which the water-soluble antioxidants were extractable, were Spinacia (Spinacia oleracea: spinach), Trifolium (clover), Medicago (Medicago sativa: alfalfa), Zea (Zea mays: corn), Nicotiana (Nicotiana tabacum: tobacco), Pennisetum and Allium (onion and garlic). In accordance with the present invention, it has been discovered that other specific species may also be used as a source of the antioxidants.